Lighting assembly

ABSTRACT

A lighting assembly includes a light engine and a light guide. The light engine edge lights the light guide and includes a control assembly that controls light output according to one or more parameters to produce light output from the lighting assembly with a desired characteristic. Lighting assemblies are combined to form a modular lighting assembly.

RELATED APPLICATION DATA

This application is a continuation of U.S. patent application Ser. No.13/440,210, filed Apr. 5, 2012, which claims the benefit of U.S.Provisional Patent Application No. 61/486,096, filed May 13, 2011, thedisclosures of which are incorporated herein by reference in theirentireties.

BACKGROUND

Energy efficiency has become an area of interest for energy consumingdevices. One class of energy consuming devices is lighting devices.Solid-state light sources, such as light emitting diodes (LEDs), showpromise as energy efficient light sources for lighting devices. Butthere remains room for new and interesting ways of configuring lightingassemblies that use solid-state light sources.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an exemplary modular lighting assembly;

FIG. 2 is a schematic block diagram of a lighting assembly that formspart of the modular lighting assembly of FIG. 1;

FIG. 3 is a schematic view of a light source assembly for a light engineof the lighting assembly of FIG. 1;

FIG. 4 is a schematic view of another modular lighting assembly;

FIG. 5 is a schematic view of another exemplary modular lightingassembly;

FIGS. 6-10 are schematic views of an exemplary lighting assembly wherean angle between light guides is changeable;

FIG. 11 is an exploded view of an exemplary light engine for thelighting assembly of FIGS. 6-10;

FIG. 12 is an end view of a first coupling member of the light engine ofFIG. 11;

FIG. 13 is an end view of a second coupling member of the light engineof FIG. 11;

FIG. 14 is a schematic view of another exemplary modular lightingassembly;

FIG. 15 is a schematic view of the modular lighting assembly of FIG. 14in a suspended configuration;

FIG. 16 is a schematic view of the modular lighting assembly of FIG. 14in a folded configuration;

FIG. 17 is a schematic view of the modular lighting assembly of FIG. 14in another folded configuration;

FIGS. 18A-18C are schematic views of exemplary modular lightingassemblies configured to illuminate a surface;

FIG. 19 is a schematic view of another exemplary modular lightingassembly configured to illuminate a surface;

FIG. 20 is a schematic view of another exemplary modular lightingassembly and includes an enlarged view of a hinged light engine;

FIG. 21 is a schematic view of another exemplary modular lightingassembly; and

FIGS. 22-25 schematically illustrate additional exemplary modularlighting assemblies.

DETAILED DESCRIPTION

Embodiments will now be described with reference to the drawings,wherein like reference numerals are used to refer to like elementsthroughout. Reference numerals without appended letters refer tocorresponding elements generically whereas reference numerals withappended letters refer to individual elements. The figures are notnecessarily to scale. Features that are described and/or illustratedwith respect to one embodiment may be used in the same way or in asimilar way in one or more other embodiments and/or in combination withor instead of the features of the other embodiments.

Aspects of this disclosure relate to a lighting assembly. Referring toFIG. 1, schematically shown are two lighting assemblies 10 that arecombined to form a modular lighting assembly 12. Each lighting assembly10 includes a light engine 14 and at least one light guide 16.

With additional reference to FIG. 2, which is a schematic block diagramof the lighting assembly 10, the light engine 14 includes a controlassembly 18 (FIG. 2), a light source assembly 20 (FIG. 2), and acoupling member 22 (FIG. 1). The coupling member 22 retains the controlassembly 18, the light source assembly 20 and one or more light guides16. In one embodiment, the coupling member 22 functions as an armatureand also functions as a heat sink for heat generated by the light sourceassembly 20. In one embodiment, the coupling member 22 includes athrough hole 24 (FIG. 1) to function as an air passage to assist incooling of the light source assembly 20. Additional informationregarding the construction of the light engine 14 may be found in U.S.Provisional Patent Application No. 61/483,431, filed May 6, 2011 andentitled Lighting Assembly.

Each light engine 14 in the modular lighting assembly 12 is configuredto supply light to one or more light guides 16. For this purpose, andwith additional reference to FIG. 3, the light source assembly 20includes at least one light source segment 26 (FIGS. 1, 2 and 3) foreach light guide 16 to which the light engine 14 is capable of supplyinglight. The coupling member 22 also includes a receptacle 28 (FIG. 1) foreach retained light guide 16. The receptacle 28 receives a portion ofthe light guide 16 that includes a light input edge 30 (FIG. 1) of thelight guide 16. In one embodiment, the light engine 14 includes at leastone light source segment 26 for each for each received light guide 16.For example, a first light engine 14A of the modular lighting assembly12 of FIG. 1 has one light source segment 26A1 to edge light a firstlight input edge 30A1 of a first light guide 16A, and a second lightengine 14B has a first light source segment 26B1 to edge light a secondlight input edge 30A2 of the first light guide 16A and a second lightsource segment 26B2 to edge light a light input edge 30B of a secondlight guide 16B.

FIG. 3 illustrates one light source segment 26 that is representative ofa light source segment 26 that edge lights a respective light input edge30 of one of the light guides 16. The light source segment 26 includesone or more light sources 32. Each light source 32 is typically embodiedas one or more solid-state devices. In one embodiment, the light sources32 are mounted to a printed circuit board (PCB) 34. The PCB 34 isthermally conductive to conduct heat that is generated by the lightsources 32. It is possible that the control assembly 18 for a lightengine 14 is implemented in circuitry that is also mounted to the PCB 34of one of the light source segments 26 retained by the light engine 14.The circuitry of the control assembly 18 includes appropriate analogand/or digital circuit components, as will be described.

Exemplary light sources 32 include solid-state devices such as LEDs,laser diodes, and organic LEDs (OLEDs). In an embodiment where eachlight source 32 is one or more LEDs, the LEDs may be top-fire LEDs orside-fire LEDs, and may be broad spectrum LEDs (e.g., emit white light)or LEDs that emit light of a desired color or spectrum (e.g., infra-redlight, red light, green light, blue light, or ultraviolet light). In oneembodiment, the light source 32 emits light with no operably-effectiveintensity at wavelengths greater than 500 nanometers (nm) (i.e., thelight source 32 emits light at wavelengths that are predominantly lessthan 500 nm). In such embodiments, phosphors (not shown) convert atleast part of the light emitted by the light source 32 tolonger-wavelength light. Referring to FIG. 2, the control assembly 18includes a driver 36 for each light source segment 26. The driver 36 iscontrolled by a control signal to deliver a drive signal to thecorresponding light source segment 26, and hence each light source 32,so as to cause the light sources 32 to generate light. The drive signalvaries an amount of power that is applied to the light source 32 to varythe light output of the light source 32 (e.g., from zero light output,or off, to a maximum light output of the light source 32).

Light from the light sources 32 of the light source segment 26 is inputinto the light guide 16. The light guide 16 is a solid article madefrom, for example, acrylic, polycarbonate, glass, or another appropriatematerial. The light guide 16 also may be a multi-layer light guidehaving two or more layers. The light guide 16 has opposed major surfaces38 and 40. Depending on the configuration of the light guide 16, thelight guide 16 has at least one light input edge 30.

As indicated, in the modular lighting assembly 12 shown in FIG. 1, eachlight guide 16A, 16B has one or more light input edges 30 to receivelight from the light source segments 26 of one or both light engines14A, 14B. In this case, the first light input edge 30A1 of the lightguide 16A is received and secured by a coupling member 22A of the firstlight engine 14A and a second light input edge 30A2 of the light guide16A is received and secured by a coupling member 22B of the second lightengine 14B. The light input edges 30A1 and 30A2 are respectively edgelit by the light source segment 26A2 of the first light engine 14A andthe light source segment 26B1 of the second light engine 14B. That is,at each light input edge 30A1, 30A2, light from the respective lightsource segment 26A2, 26B 1 is input into the light guide 16A through thelight input edges 30A1 and 30A2. For this purpose, light output fromeach light source segment 26A2, 26B1 is directed toward the respectivelight input edge 30A, 30B. Additional optical elements (e.g., lenses,reflectors, etc.) adjacent one or both of the light source segments 26and the light input edges 30A, 30B may be present to assist in inputtingthe light into the light guide 16A. The light guide 16B is received andsecured by the coupling member 22B of the second light engine 14B. Thelight input edges 30B of the second light guide 16B is edge lit by thelight source segment 26B2 of the second light engine 14A. The edge ofthe second light 16B distal the light input edge 30B is not connected toanother light engine 14 and, consequently, is edge lit only along thelight input edge 30B.

The light guides 16 shown in the appended figures are generallyrectangular. But other shapes are possible, and the light guides 16 neednot be planar. Other exemplary, but not illustrated, light guide shapesinclude a disk, a dome, a hollow cylinder, a hollow and frustrated coneor pyramid, or a globe or a shape approximating the bulbous shape of aconventional incandescent bulb, each configured to include one or morelight input edges. In one embodiment, a three dimensional configurationfor the light guide 16 is established using planar or curved lightguides that are arranged in a three-dimensional geometric (e.g.,polygonal) configuration. In the case where the light guide 16 isbasically rectangular (e.g., the illustrated embodiments), the lightguide 12 has four edges. Other geometries for the light guide 16 resultin a corresponding number of edges. Depending on the geometry of thelight guide 16, each edge may be straight or curved, and adjacent edgesmay meet at a vertex or join in a curve.

Once input into the light guide 16, the light propagates through thelight guide 16 by total internal reflection (TIR) at the opposed majorsurfaces 38, 40. For purposes of this disclosure, any light inputsurface of the light guide 16 is considered a light input edge, even ifit is located on one of the major surfaces 38, 40 or forms part of alight turning and/or homogenizing structure of the light guide 16 tointroduce light between the major surfaces 38, 40 in a manner thatallows the light to propagate along the light guide 16 by total internalreflection at the major surfaces 38, 40.

Length and width dimensions of each of the major surfaces 38, 40 aremuch greater than, typically ten or more times greater than, thethickness of the light guide 16. For instance, in the rectangularembodiments shown in the appended figures, the length (measured from thelight input edge 30 to an opposite edge distal the light input edge 30)and the width (measured along the light input edge 30) of the lightguide 16 are both much greater than the thickness of the light guide 16.The thickness is the dimension of the light guide 16 in a directionorthogonal to the major surfaces. The thickness of the light guide 16may be, for example, about 0.1 millimeters (mm) to about 10 mm. Thelight guide 16 may be rigid or flexible.

The light guide 16 includes light-extracting elements 42 (shownschematically in FIG. 1 as circles) in or on at least one of the majorsurfaces 38, 40. Light-extracting elements 42 that are in or on a majorsurface 38, 40 will be referred to as being “at” the major surface 38,40. Each light-extracting element 42 functions to disrupt the totalinternal reflection of the propagating light that is incident on thelight-extracting element 42. In one embodiment, the light-extractingelements 42 reflect light toward the opposed major surface so that thelight exits the light guide 16 through the opposed major surface.Alternatively, the light-extracting elements 42 transmit light throughthe light-extracting elements 42 and out of the major surface 38, 40 ofthe light guide 16 having the light-extracting elements. In anotherembodiment, both of these types of light-extracting elements 42 arepresent. In yet another embodiment, the light-extracting elements 42reflect some of the light and refract the remainder of the lightincident thereon. Therefore, the light-extracting elements 42 areconfigured to extract light from the light guide 16 through one or bothof the major surfaces 38, 40. The light-extracting elements 42 may bearranged to output light over part or all of one or both of the majorsurfaces 38, 40.

The light-extracting elements 42 may be at one or both of the majorsurfaces 38, 40 through which light is emitted, or at the opposite majorsurface 38, 40. Light guides having such light-extracting elements 42are typically formed by a process such as stamping, molding, embossing,extruding, laser etching, chemical etching, or another suitable process.Light-extracting elements 42 may also be produced by depositing curablematerial on the light guide 16 and curing the deposited material usingheat, UV-light or other radiation. The curable material can be depositedby a process such as printing, ink jet printing, screen printing, oranother suitable process. Alternatively, the light-extracting elements42 may be inside the light guide between the major surfaces 38, 40(e.g., the light-extracting elements 42 may be light redirectingparticles and/or voids disposed in the light guide).

The light-extracting elements 42 are configured to extract light in adefined intensity profile, such as a uniform intensity profile, over therelevant major surface 38, 40 and/or to extract light in a defined lightray angle distribution. Using variations in the light-extractingelements 42, the major surfaces 38, 40, or portions thereof, can havedifferent intensity profiles and/or light ray angle distributions.Intensity profile refers to the variation of intensity with positionwithin a light-emitting region (such as the area of the major surface38, 40 from which light is emitted). Light ray angle distribution refersto the variation of intensity with ray angle (typically a solid angle)of light emitted from a light-emitting region (such as the area of themajor surface 38, 40 from which light is emitted).

Exemplary light-extracting elements 42 include light-scatteringelements, which are typically features of indistinct shape or surfacetexture, such as printed features, ink jet printed features,selectively-deposited features, chemically etched features, laser etchedfeatures, and so forth. Other exemplary light-extracting elements 42include features of well-defined shape, such as V-grooves, lenticulargrooves, and features of well-defined shape that are small relative tothe linear dimensions of the major surfaces 38, 40, which are referredto herein as micro-optical elements. The smaller of the length and widthof a micro-optical element is less than one-tenth of the larger of thelength and width of the light guide 16, and the larger of the length andwidth of the micro-optical element is less than one-half of the smallerof the length and width of the light guide 16. The length and width ofthe micro-optical element are measured in a plane parallel to the majorsurface 38, 40 of the light guide 16 for flat light guides 16 or along asurface contour for non-flat light guides 16.

Micro-optical elements are shaped to predictably reflect light orpredictably refract light. However, one or more of the surfaces of themicro-optical elements may be modified, such as roughened, to produce asecondary effect on light output. Exemplary micro-optical elements aredescribed in U.S. Pat. No. 6,752,505 and, for the sake of brevity, willnot be described in detail in this disclosure. The micro-opticalelements may vary in one or more of size, shape, depth or height,density, orientation, slope angle, or index of refraction such that adesired light output from the light guide 16 is obtained over thecorresponding major surface 38, 40.

As indicated, the lighting assembly 10 includes the light engine 14. Thecoupling member 22 of the light engine 14 functions to retain the lightguide 16 and to retain, as part of the light engine 14, the light sourcesegment 26. In addition, the light engine 14 aligns the light input edge30 with the light source segment 26 in an arrangement for inputtinglight from the light source segment 26 into the light input edge 30.Additionally, the light engine 14 dissipates heat that is generated bythe light source segment 26.

The coupling member 22 is supported in an appropriate manner and so thatthe light guide 16 has a desired orientation. For instance, the couplingmember 22 may be coupled to an architectural surface (e.g., a wall or aceiling) by a retaining member 43. In the embodiment of FIG. 1, theretaining member 43 is a cable (e.g., “aircraft cable”). Other exemplaryretaining members 43 include a track, a pole, a rod, a wire, electricalwire that supplies electricity to the lighting assembly 10, screws, abracket, etc. In other embodiments, the lighting assembly 10 may beembodied as a floor lamp, a table lamp, a task light, or other lightingdevice.

Different types of light guides 16 may be used with the light engine 14.Also, different types of light source assemblies 20 or light sourcesegments 26 may be used in the light engine 14. Also, depending on howthe modular light assembly 12 is arranged, the light guide 16 may beedge lit at one or more than one light input edge 30. In still otherembodiments, the light engine 14 may light two or more light guides 16,and the angle between the light guides 16 may be varied. The user of themodular lighting assembly 12 may also be interested in obtainingdifferent illumination profiles from the modular lighting assembly 12.For these reasons, it may be desirable to control the light generated bythe light sources 32 to achieve desired light output characteristicsfrom the modular lighting assembly 12 as a whole.

Control over the light sources 32 will now be described for a number ofoperational situations with reference to FIG. 2. To effectuate controlover the light sources 32, the control assembly 18 includes a controller44. In an embodiment, the controller performs (e.g., carries out)logical operations, typically in response to instructions (e.g., byexecuting executable code) that is stored on a non-transitory computerreadable medium (e.g., a magnetic, optical or electronic memory). In theillustrated embodiment, the controller 44 is a microcontroller and, inother embodiments, the controller 44 is a general-purpose processor oran application specific integrated circuit (ASIC). The control assembly18 of the illustrated embodiment includes a memory 46 for storing dataand executable instructions. At least part of the memory 46 may beembedded within the controller 44.

The control assembly 18 includes at least one sensor for detectingvarious conditions (e.g., operational states corresponding to programobjects) associated with the modular lighting assembly 12. Exemplarysensors include a light guide sensor 48, an angle sensor 50, a lightsource sensor 52, and a light characteristic sensor 54. Additionaldetails of the sensors will be described below in connection withcontrol functions of the control assembly 18.

In one embodiment, the control assembly 18 is configured to communicatewith other electronic devices, such as control assemblies 18 of otherlight engines 14 in the modular lighting assembly 12 or a user inputdevice 60. For this purpose, the control assembly 18 includes aninterface 56 that establishes operative communication with one or moreother control assemblies 18 and an interface 58 that establishesoperative communication with a user input device 60. The user inputdevice 60 receives input commands from an operator (e.g., a user) andthe user input device 60 communicates those commands to the controller44 via the interface 58 to effectuate control over the modular lightingassembly 12. Exemplary user input devices 60 include a keypad, adedicated control panel for the modular lighting assembly 12, a portableelectronic device (e.g., a mobile phone, a tablet computer, etc.), acomputer, or other similar device. In other embodiments, the interface58 receives input commands from an automated source, such as a computerthat is programmed to control the lighting assembly 10.

The light engine 14 receives electrical power to operate the controlassembly 18 and illuminate the light sources 32 via power connectors 61.The power connectors 61 of at least one of the light engines 14 in themodular lighting assembly 12 are configured to connect to electricalwires (not shown) that connect to a power outlet, a building'selectrical system, or another source of electrical power. Additionalpower connectors 61 of the light engine 14 are configured to connect toelectrical conductors that connect to power connectors 61 in anotherlight engine 14 of the modular lighting assembly 12. In this manner,electrical power may be fed from one light engine 14 to another lightengine 14 in the modular lighting assembly 12. Electrical power may bedistributed through the modular lighting assembly 12 in a daisy-chainarrangement.

In one embodiment, the light guide 16 includes electrical conductors 62that establish an electrical pathway between a pair of light engines 14.With brief departure to the embodiment of FIG. 1, one conductor 62 isattached to a side edge of the light guide 16 and a second conductor 62is attached to an opposite side edge of the light guide 16. In otherembodiments, the conductors are located on one or both of the majorsurfaces 38, 40. The conductors 62 are typically implemented using metalwires or films, but could be implemented using conductive particles in abinder or another suitable way. Near the light input edge 30 of thelight guide 16, the conductors 62 are located so that when the lightguide 16 is inserted into the receptacle 28 of the coupling member 22,the conductors 62 make physical and electrical contact withcorresponding ones of the connectors 60.

With continuing reference to FIG. 2, the conductors 62 alternatively oradditionally may be used by light engines 14 as signaling conductors toexchange data signals between the respective control assemblies 18. Inthis embodiment, the interface 56 couples the data signals to theconductors 62 as represented by dashed lines in FIG. 2. Therefore, inone embodiment, there are conductors 62 for the distribution of power,in one embodiment, there are conductors 62 for the exchange of datasignals, in one embodiment, there are separate conductors 62respectively for the distribution of power and for the exchange of datasignals, or in one embodiment, there are conductors 62 for thedistribution of power and data signals are optionally superposed on theconductors 62 for power distribution. Other ways of communicatingbetween or among light engines 14 are possible and the interfaces 56 maybe configured accordingly. Exemplary communication techniques includeoptical communication (e.g., via infrared (IR) or visible lighttransceivers), wireless communication (e.g., via radio frequency (RF)transceiver such as BLUETOOTH®, WiFi), or signal exchange throughconductors that travel between light engines 14 along paths other thanthrough or on the light guide 16. In the case of optical communication,signals may be exchanged through the light guide 16.

With brief departure to FIG. 4, other types of conductors between pairsof light engines 14 are illustrated. In one embodiment, conductors 64(represented by a broken line in FIG. 4) are embedded in a light guide16 so as to extend between light engines 14A and 14C. In otherembodiments, the conductors extend between light engines 14 externallyof the light guide 16. For example, conductors 66 (represented with abold line in FIG. 4) extend between the light engines 14A and 14Bexternally of the light guide 16. In other examples, a conductor (notshown) extends between the light engines 14 through the retainingmembers 43.

With continuing reference to FIG. 2, in one embodiment, the controlassembly 18 is configured to detect the presence or absence of a lightguide 16 in a receptacle 28 (FIG. 1) of the light engine 16. When alight guide 16 is not present, the control assembly 18 maintains eachlight source 32 in the light source segment 26 for the receptacle 28that does not have a light guide 16 in an off state. When a light guide16 is present, the control assembly 18 turns on one or more of the lightsources 32 in the light source segment 26 for the receptacle 28 in whichthe light guide 16 is present to edge light the light guide 16. Thenumber of light sources 32 that are turned on and the output intensityof the light sources 32 depend on a desired intensity output from thelight guide 16 and the light guide type.

The presence or absence of the light guide 16 is detected by the lightguide sensor 48. In one embodiment, the light guide sensor 48 is assimple as a switch that is forced to close or open when the light guide16 is installed in the receptacle 28. Other light guide sensors 48include an optical detector that senses a change in light based onpresence or absence of the light guide 16. Presence or absence of thelight guide 16 alternatively may be communicated to the control assembly18 by a user via the user input device 60 and interface 58. Other, moresophisticated, light guide sensors 48 will be described in the followingparagraphs.

As indicated, it may be desirable to coordinate light output by thelight source segment 26 and other operations of the light engine 14 withthe type of light guide 16 that is positioned to receive light from thelight source segment 26. In this manner, one light engine 14 may be usedwith multiple light guide types. Light guide type may be defined by oneor more characteristics of the light guide 16. These characteristicsinclude, but are not limited to, size of the light guide 16 (e.g.,length of the light guide 16 in a direction extending from the lightinput edge 30, or a fraction of the width of the receptacle 28 that thelight guide 16 occupies), configuration of light extracting elements 42,presence or absence of conductors 62 for coupling of power between lightengines 14, presence or absence of conductors 62 for exchanging datasignals between light engines 14, number and position of light inputedges, color filtering or wavelength shifting features of the lightguide 16, the directionality of the light guide 16 (e.g., whether thelight guide is configured to extract light input through only one lightinput edge or through more than one light input edge), and so forth.

The light guide type may be communicated to the control assembly 18 by auser via the user input device 60 and interface 58. This user may be anend user of the modular lighting assembly 12, an installer of themodular lighting assembly 12, or a manufacturer of the modular lightingassembly 12 or components thereof. Alternatively, the light guide typeis detected by the light guide sensor 48. In one embodiment, the lightguide 16 includes an identifier 68 that is read or sensed by the lightguide sensor 48. The identifier 68 may provide a value that is used inconjunction with stored information to determine the characteristics ofthe light guide 16 or may directly convey information about thecharacteristics of the light guide 16. The light guide sensor 48 isconfigured to be compatible with the identifier 68. Exemplary lightguide sensors 48 and identifiers 68 include a radio frequencyidentification (RFID) reader and RFID tag; a barcode reader and abarcode; a microchip reader and a microchip where connection between thereader and the microchip is established with conductors, wirelessly by aradio frequency signal, or optically; a memory reader and a memory(e.g., a flash memory or other non-transitory memory retained by thelight guide 16); and an optical reader and an optically readable patternon the light guide 16 (e.g., an etched pattern, a pattern of depositedmaterial, etc.). In another embodiment, the light guide sensor 48 is aseries of pairs of electrical contacts and the identifier 68 is a seriesof electrical conductors that are arranged to selectively bridge pairsof the contacts based on the light guide type. The electrical conductorseffectively form a “readable” pattern of conductive strips. The controlassembly 18 identifies the pairs of bridged contacts to determine thelight guide type or the light guide characteristics. In anotherembodiment, the light guide sensor 48 includes a series of switches orpressure sensors and, as the identifier 68, the light guide 16 includesa pattern of protrusions or indentations that selectively close (oropen) the switches or make contact with the pressure sensors based onthe light guide type. The control assembly 18 identifies which switchesor pressure sensors that are affected by the light guide 16 to determinethe light guide type or the light guide characteristics.

The light input to the light guide 16 is coordinated with the lightguide type. For instance, to produce a defined illuminance at the majorsurface of the light guide, a longer light guide 16 is edge lit with agreater intensity of light than a shorter light guide 16. The intensityof the light may be controlled by one or both of controlling the numberof light sources 32 of the light source segment 26 that are turned on orby controlling the intensity of the light input to the light guide 16from each light source 32. Varying a drive current that is applied tothe light sources 32 by the driver 36 may be used to vary the intensityof light input to the light guide 16. As another example, a light guide16 with a first arrangement of light extracting elements 62 may be edgelit with a combination of light sources 32 positionally matched to thefirst arrangement of light extracting elements, and a second arrangementof light extracting elements 62 may be edge lit with differentcombination of light sources 32 positionally matched to the secondarrangement of light extracting elements. Other light output or controladjustments are made by the control assembly is based on thedetermination of the light guide type.

More than one type of light source segment 26 may be used in the lightengine 14. To coordinate operation of the control assembly 18 with thelight source segment 26, the control assembly 18 determines the type ofthe light source segment 26. The light source segment type may becommunicated to the control assembly 18 by a user via the user inputdevice 60 and interface 58. This user may be an end user of the modularlighting assembly 12, an installer of the modular lighting assembly 12,or a manufacturer of the modular lighting assembly 12 or componentsthereof. Alternatively, the light source segment type is represented bya light source segment identifier 70 that is read by the light sourcesensor 52 (e.g., each light source segment 26A and 26B has acorresponding light source segment identifier 70A and 70B that is readby the light source sensor 52). Parameters of the light source segmentrepresented by the light source segment type include an identity of thelight sources 32 of the light source segment 26, the number of lightsources 32, the physical layout of the light sources 32, the electricalpower requirements of the light sources 32, the light outputcharacteristics of the light sources 32, including intensity of theemitted light per unit of drive current and spectral characteristics ofthe emitted light. In one embodiment, the control assembly 18 identifiesthe light source segment type (e.g., as indicated by a reference numberor code) and determines the corresponding characteristics of the lightsource segment 26 using a look-up table or database that is stored inthe memory 46. In another embodiment, the characteristics of the lightsource segment 26 are determined directly from the light source segment26 (e.g., from the identifier 70). The light source sensor 52 and thelight source segment identifier 70 may be embodied in any suitablemanner, including the above-described manners of implementing the lightguide sensor 48 and the identifier 68.

In one embodiment, the control assembly 18 stores one or both of aparameter set for driving the light sources 32 based on the identifiedtype of the light source segment 26 and a parameter set for driving thelight sources 32 based on the identified type of the light guide 16.Using the stored parameters, the controller 44 is configured to adjustthe drive signal output by the drivers 36 to the light sources 32 basedon the identified type of the light guide 16 and/or the identified typeof the light source segment 26. In another embodiment, characteristicsof the light source assembly 20 are identified for the light sourceassembly 20 as a whole, rather than at the light source segment 26level.

In some instances, one of the light guides 16 in the modular lightingassembly 12 is edge lit by one light engine 14. As an example, in theillustration of FIG. 1, the light guide 16B is supplied with light fromthe connected light engine 14B. In this situation, all of the lightavailable to the light guide 16B is generated by one light sourcesegment 26B2 under the control of the control assembly 18 in thecorresponding light engine 14B. The control assembly 18 controls acorresponding driver 36 and, in turn, the corresponding light sources32, to generate light in a manner that produces a desired lightintensity from the light guide 16B.

In other instances, the light guide 16 is edge lit with two or morelight engines 14. As an example, in the illustration of FIG. 1, thelight guide 16A is provided with light from two light engines 14A and14B. In this situation, if each light engine 14A, 14B that inputs lightinto the light guide 16A were to input light into the light guide 16A asif it were the only light engine to supply light to the light guide 16A,then the intensity of the light output by the light guide 16A would betwice obtained with the light guide 16A illuminated by only one lightengine 14A or 14B. Therefore, the control assembly 18 of at least one ofthe light engines 14A, 14B is configured to coordinate its lightgeneration with that of any other light engine that supplies light tothe same light guide.

In one embodiment, the coordination is implemented by communicationbetween the control assemblies 18. Communication may take place as anexchange of data signals between the control assemblies 18. In oneembodiment, one of the control assemblies 18 assumes a master role andanother of the control assemblies 18 assumes a slave role in which themaster control assembly 18 issues operating commands to the slavecontrol assembly 18. Light generation by the light source assembly 20in, e.g., the light engine 14A having the slave control assembly 18 iscontrolled by the operating commands received from the master controlassembly 18. In another embodiment, the detection of another lightengine 14A connected to the light guide 16A is used as an input commandto change the intensity of the light generated by the light sourcesegment 26B 1 of the light engine 14B and input to the light guide 16A.For instance, in the case where conductors 62 are present, the lightengine 14A may place a detectable load on the conductors 62 or signal tothe light engine 14B via the conductors 62. If the light engine 14A ispresent, it may be assumed that the light engine 14A will input lightinto the light guide 16A. Under this assumption, each of the lightengines 14A, 14B reduces its light output to the light guide 16A by onehalf, or one light engine 14A, 14B does not input light into the lightguide 16A and allow the other light engine 14B, 14A to edge light thelight guide 16A.

In another embodiment, the control assembly 18 of the light engine 14Bdetects the presence of a second light engine 14A that inputs light intothe light guide 16A using the light characteristic sensor 54 (FIGS. 2and 3). For this purpose, the light characteristic sensor 54 is aphoto-detector (e.g., a photodiode) that is configured to detect lightdirected toward the light engine 14B by another light engine 14A throughthe light guide 16A. In one embodiment, the light characteristic sensor54 is positioned adjacent the light input edge 30B of the light guide16A to detect light that exits the light input edge 30B in a directiontoward the light engine 14B. In the embodiment of FIG. 3, for example,the light characteristic sensor 54 is mounted to the PCB 34 with thelight sources 32 of the light source segment 26B1. In one embodiment,the controller 44 adjusts the drive signal output by the driver 36 tothe light sources 32 based on an intensity of incident light detected bythe sensor 54. In one embodiment, when the light characteristic sensor54 detects light of an intensity above a predetermined threshold, adetermination is made that light is input into the light guide 16A byanother light engine 14A. In this case, the control assembly 18 reducesthe intensity of light input into the light guide 16A (e.g., to one halfof the intensity that the light engine 14B would have produced had therebeen no detection of light from the other light engine 14A). The otherlight engine 14A makes the same determination and also reduces its lightoutput. Therefore, the light guide 16A outputs light with a desiredintensity regardless of the number of light engines coupled andinputting light to light guide 16A.

The light characteristic sensor 54 may be used for other purposes. Thelight characteristic sensor 54 may be configured to detect light fromthe environment surrounding the modular lighting assembly 12 rather thanor in addition to light directed toward the light engine 14B through thelight guide 16A. In that case, the light characteristic sensor 54 mayadditionally include, or alternatively may be, an ambient light sensorthat is mounted on the coupling member 22 (or other location, possiblyapart from the modular lighting assembly 12) with an orientation todetect light from a desired location (e.g., one of the light guides 16or a surface illuminated with the modular lighting assembly 12). In oneembodiment, the light characteristic sensor 54 detects ambient lightlevel and the control assembly 18 adjusts light output by the lightsources 32 in accordance with the detected level of ambient light tocontrol the overall light level in the space illuminated by the modularlighting assembly 12.

In one embodiment, the light characteristic sensor 54 detects the colorof light and the control assembly 18 adjusts light output from the lightsources 32 in accordance with the detected light color to control thecolor of light in the space illuminated by the modular lighting assembly12. In one embodiment, color adjustment is made in response to thedetection of the color of ambient light. In another embodiment, coloradjustment is made in response to the detection of the color of lightexiting the light guide from the light input edge 30. For this purpose,the light source segments 26 include light sources 32 of differentcolors controlled to emit light at different intensities. The light fromthe light sources of different color combines to provide light of adesired color from the modular lighting assembly 12. The different colorlight sources 32 may include a combination of light sources selectedfrom broad-spectrum white light sources, white light sources that areskewed toward outputting red light (e.g., “warm” light sources), whitelight sources that are skewed toward outputting blue light (e.g., “cool”light sources), red light sources, blue light sources, green lightsources, and so forth.

In one embodiment, the light characteristic sensor 54 is a pixelatedsensor. An exemplary pixelated sensor has two or more photo-detectorsarranged in a one- or two-dimensional array, or some otherconfiguration. Exemplary pixelated sensors include a CMOS sensor, acharge-coupled device (CCD) sensor, or other active-pixel sensor (APS).In one embodiment, a grating is placed in front of the pixelated sensor.The grating splits incident light into spectral bands that areseparately detected by the pixels of the sensor 54. Analysis of theoutput of the sensor 54 can be used to determine the spectrum of theincident light.

In one embodiment, a pixelated version of the light characteristicsensor 54 is used as an ambient light sensor to assess light produced bythe modular lighting assembly 12 and incident on a surface. Analysis ofthe output from the sensor 54 determines the intensity or color of thelight or the area covered by the light on the surface, and to adjust thelight output by the light source assembly 20 to achieve a desiredintensity or illumination coverage, if not already obtained.

A number of additional functional operations of the light engine 14 arepossible. As indicated, in one embodiment, two or more controlassemblies 18 coordinate operation of the light sources 32. For thispurpose, data signals are exchanges between or among the controlassemblies 18. The coordination between or among the control assemblies18 may include discovery of the configuration of the modular lightingassembly 12. The configuration of the modular lighting assembly 12 mayinclude one or more of: the number of light guides 16, the type of eachlight guide 16, the number of light engines 14, the number and type oflight source segment 26 in each light engine 14, the characteristics ofeach light source segment 26, and the relationship between the lightsource segments 26 and their respective light input edges 30 of thelight guides 16. Once this information is determined, light emissionfrom the light sources 32 is controlled to obtain a desired lightingprofile from the modular lighting assembly 12. The characteristics thatdefine a lighting profile of the modular lighting assembly 12 includethe color, intensity, and spatial and temporal variations of intensityand color of each light guide 16.

A desired lighting profile may be a default lighting profile that ispredetermined by a manufacturer. There may be more than one defaultlighting profile with each default lighting profile corresponding to adifferent potential configuration of the modular lighting assembly 12.Alternatively, the installer or user of the modular lighting assembly 12may define one or more predetermined lighting profiles. Thesepredetermined lighting profiles may correspond to different situations,such as time of day, an activity in which the user is engaged,availability of light from other lighting assemblies or ambient sources,and so forth.

The predetermined lighting profiles and any other data used by thecontrol assembly 18 may be stored in the memory 46. The memory 46 mayinclude one or both of volatile and non-volatile components. Also, thememory 46 may include any appropriate drives, readers or players for thedata storage component (e.g., media component) of the memory 46.

Various ways to communicate among the control assemblies 18 and betweenthe user input device 60 and the control assembly 18 have beendiscussed. In one embodiment, the control assembly 18 may interface witha network (not shown) and have a network address (e.g., an internetprotocol (IP) address) so as to receive and send data over the network.The network may have a physical backbone (e.g., network cables) or maybe wireless. Commands may be transmitted to the control assembly 18 overthe network, such as a command to the turn the modular lighting assembly12 on or off, or a command to use a predetermined lighting profile.

Another exemplary modular lighting assembly 12 is illustrated in FIG. 5.In this embodiment, the modular lighting assembly 12 includes lightengines 14 and light guides 16D, 16E that interconnect to form an oval.In the embodiment of FIG. 5, the modular lighting assembly 12 issupported by retaining members 43 that are connected to two of the lightengines 14. The two light engines 14 that are connected to the retainingmembers 43 each support two arcuate light guides 16E and the arcuatelight guides 16E are connected to additional light engines 14 that, inturn, support the rectangular light guides 16D. In the illustratedembodiment, the light guides 16D, 16E each includes a notch 72 havingedges that are received by the receptacle 28 of a respective lightengine 14. At least one edge of the notch 72 forms the light input edge30 (not shown in FIG. 5). A mechanically stable modular lightingassembly 12 is constructed by interconnecting the light engines 14 andthe light guides 16D, 16E. Other configurations and shapes for themodular lighting assembly 12 are possible. The number of configurationsis potentially limitless since the configurations can be created withdifferent shaped light guides 16 and light engines 14 of differentcharacteristics and shapes.

In the embodiments illustrated thus far, the light guides 16 of themodular lighting assembly 12 are in the same plane. This need not be thecase. The light engine 14 may be configured to retain light guides 16with an angle between the major surfaces 38, 40 of respective lightguides 16, such as 90 degrees, 45 degrees, 30 degrees, or any otherdesired angle. In some embodiments, such as those shown in FIGS. 1, 3and 5, the angle between the major surfaces 38, 40 is fixed.

With additional reference to FIGS. 6-10, the angle between majorsurfaces 38, 40 of two light guides 16F, 16G (collectively referred toas light guides 16) that are retained by a light engine 14 may beadjustable. In these embodiments, the light engine 14 is hinged so thatthe light guides 16 are pivotable with respect to each other. The anglemay be set by the user of the lighting assembly 10. As depicted byarrows 74 in FIGS. 6 and 7 that represent light rays emitted from themajor surfaces 38 of the light guides 16, the lighting profile may bechanged by changing an angle α (alpha) between the light guides 16.Although not illustrated in FIGS. 6 and 7, light also may be emittedfrom the major surfaces 40, and the directional properties of the lightemitted from the major surfaces 40 would also change in accordance withchanges in the angle α between the light guides 16. Changing the angle αalso changes the light ray angle distribution of, and the size of thearea illuminated by, the lighting assembly 10. FIGS. 8-10 illustrate anexample of a lighting assembly 10 in which the angle α between the lightguides 16 has been adjusted to different values.

With additional reference to FIG. 11, illustrated is an embodiment ofthe light engine 14 that retains a first light guide 16F in a firstcoupling member 76 and a second light guide 16G in a second couplingmember 78 (the light guides 16F, 16G are not shown in FIG. 11). Thelight engine 14 is hinged so that the angle α between the couplingmembers 76, 78 is adjustable, and hence the angle between the lightguides 16F, 16G is adjustable.

To further illustrate the light engine of FIG. 11, opposite end views ofthe first coupling member 76 and the second coupling member 78 arerespectively illustrated in FIGS. 12 and 13. The first coupling member76 retains the light guide 16F (not shown in FIG. 12) in a receptacle 28of the first light coupling member 76 and edge lights the light guide16F with a light source segment 26 of the first light coupling member76. Similarly, the second coupling member 78 retains the light guide 16G(not shown in FIG. 13) in a receptacle 28 of the second light couplingmember 78 and edge lights the light guide 16G with a light sourcesegment 26 of the second light coupling member 78.

The first coupling member 76 includes a sleeve 80 having a cylindricalbore that axially receives a pin 82 of the second coupling member 78. Inthe illustrated embodiment, the pin 82 and the sleeve 80 are rotatablerelative to each other, but the pin 82 is fixed relative to the rest ofthe second coupling member 78 and the sleeve 80 is fixed relative to therest of the first coupling member 76. In one embodiment, relativerotation of the first coupling member 76 and the second coupling member78 is limited. For example, in the illustrated embodiment, the firstcoupling member 76 includes a limit pin 84 that is axially received in alimit slot 86 of the second coupling member 78. Relative rotation of thefirst coupling member 76 and the second coupling member 78 stops whenthe limit pin 84 contacts either end 88 of the limit slot 86. Thelocations of the ends 88 can be configured to provide a desired range ofangular movement, selectable by the user.

In one embodiment, the light sources 32 are controlled in accordancewith the angle between light guides 16. For example, when the angle issmall, fewer light sources 32 may be illuminated than when the angle islarge, or when the angle is small, the intensity of light output by thelight sources 32 may be less than when the angle is large. The anglebetween light guides 16 is defined by the angle between the firstcoupling member 76 and the second coupling member 78.

The angle between the first and second coupling members 76, 78 isdetected by the angle sensor 50 (FIG. 2). The controller 44 controls thelight source assembly 20 as a function of the angle α between the lightguides 16 in response to the output of the angle sensor 50. In oneembodiment, the angle sensor 50 is an analog device, such as apotentiometer. In one embodiment, the pin 84 is coupled to the wiper ofthe potentiometer and the body of the potentiometer is coupled to thesecond coupling member 78. In another embodiment, the pin 84 providesthe wiper of the potentiometer and the slot 86 contains the resistiveelement of the potentiometer. As the pin 84 moves in the slot 86, thecorresponding change in resistance is detected (e.g., as a correspondingchange in voltage or other value input to the controller 44). The anglesensor 50 may be implemented in other manners. Other exemplary anglesensors 50 include rotational encoders and linear encoders incorporatingmechanical, optical, or other suitable transducers.

With additional reference to FIGS. 14-17, a modular lighting assembly 12is formed by connecting together lighting assemblies 10 with hingedlight engines 14. In the illustrated embodiments, the modular lightingassembly 12 is formed by connecting one end of a light guide 16 to onehinged light engine 14 and an opposite end of the light guide 16 toanother hinged light engine 14. This is repeated for another light guide16, but in the illustrated embodiment, the two end light guides 16 areconnected to only light engine 14. As a result, the modular lightingassembly 12 has an end, or first, light guide 90 connected to a firstlight engine 92, which is also connected to a second light guide 94. Thesecond light guide 94 is connected to a second light engine 96, which isalso connected to a third light guide 98. The third light guide 98 isconnected to a third light engine 100, which is also connected toanother end, or fourth, light engine 102.

In the embodiment of FIG. 14, the modular lighting assembly 12 is shownin an extended configuration. The extended configuration is obtained bypositioning the first and second coupling members 76, 78 of the hingedlight engines 14 in relative positions so that the angle betweenadjacent light guides 16 is 180 degrees.

In FIG. 15, the modular lighting assembly 12 of FIG. 14 is shown in anextended configuration and vertically mounted using retaining members 43that are connected to the first and third light engines 92, 100.Alternatively, the modular lighting assembly 12 can be mounted with thelight guides 16 horizontal.

In FIG. 16, the modular lighting assembly 12 of FIG. 14 is shown in apartially folded configuration. The partially folded configuration isobtained by positioning the first and second coupling members 76, 78 ofthe hinged light engines 14 in relative positions so that the anglesbetween adjacent light guides 16 are less than 180 degrees. In FIGS.14-17, the light engines 14 alternate in orientation (i.e., the secondlight engine 96 faces in an opposite direction from the first and thirdlight engines 92, 100). This allows the modular lighting assembly 12 tobe fan folded, which is also referred to as accordion folded. In otherembodiments, although not illustrated, all light engines 14 face in thesame direction to permit a different folding pattern. Also, the modularlighting assembly 12 may be suspended or mounted in a foldedconfiguration.

In FIG. 17, the modular lighting assembly 12 of FIG. 14 is shown in afully folded configuration, which is obtained by minimizing the hingeangles of the light engines 14. This configuration may be employed for alighting application, or may be used for storing the modular lightingassembly 12 or for packaging of the modular lighting assembly 12 if soldpreassembled.

Turning now to FIGS. 18A-18C, embodiments of the modular lightingassembly 12 having at least one light engine 14 and at least two lightguides 16 are illustrated in an application in which the modularlighting assembly 12 is used to illuminate a surface 104. The surface104 may be a table top, a floor, a wall, a ceiling, or other surface.The light extracting elements 42 (FIG. 1) typically extract light fromthe light guide 16 in a direction away from a light-emitting surface ofthe light guide 16 (e.g., one or both of the major surfaces 38 or 40)and away from the light sources 32 that generates the light. Thisconfiguration typically produces an illumination profile at the surface104 having an illuminated region 105 associated with each light guide 16and a darker region between the illuminated regions 105. The embodimentsshown in FIGS. 18A-18C, however, each employ different means foroutputting at least part of the light output from each light guide 16with a vector component directed towards the light sources 32 such thatthe first region 105 illuminated by one light guide is contiguous oroverlaps with the second region 105 illuminated by the other lightguide.

In the embodiment of FIG. 18A, the modular lighting assembly 12 includesa first light guide 16K and a second light guide 16L. Each light guide16K, 16L includes two light input edges 30 (FIG. 1) located at oppositeends of the light guide 16K, 16L. Each light input edge 30 is edge litby light from a corresponding light engine 14 (e.g., light engines 14Hand 14I for light guide 16K and light engines 14I and 14J for lightguide 16L). The light from each light engine 14 is input to therespective light guide 16K, 16L in a direction away from the light inputedge 30 through which light is input, and exits the light guide 16K, 16Lin a direction away from the respective light input edge 30 and awayfrom the major surface 38. Arrow 108 represents light from the lightengine 14H that is input to the light guide 16K in a first direction andexits through major surface 38 (the surface 38 in the illustratedembodiment being a light emitting surface). Arrow 110 represents lightfrom the light engine 14I that is input to the light guide 16K in asecond direction opposite from the first direction and exits throughmajor surface 38. The opposite directions of light input by the lightengines 14H and 14I result in a light ray angle distribution 106 thatincludes light traveling in directions away from the major surface 38and away from each of the light input edges 30 of the light guide 16K.Relative to the light engine 14I, the light engine 14H performs thefunction of means for outputting at least part 108 of the light outputfrom the light guide 16K with a vector component directed towards thelight engine 14I such that the region 105 illuminated by the light guide16K is contiguous with the region 105 illuminated by the light guide16L.

In one embodiment, the control assembly 18 of one of the light engines14 that supplies light to the light guide 16 is configured to adjust thelight output from the light sources 32 to the light guide 16 to maintaina defined illumination within the region 105 that is illuminated bylight output from the light guide 16 regardless of an intensity, withina defined range, of light received at the light input edge 30 that isedge lit with the other light engine 14.

In another embodiment, shown in FIG. 18B, the light guides 16K, 16L areedge lit by the light engine 14 and a transmissive light redirectingmember 112 is adjacent each light guide 16K, 16L. The transmissive lightredirecting member 112 associated with light guide 16K performs thefunction of means for outputting at least part 114 of the light outputfrom the light guide 16K with a vector component directed towards thelight engine 14 such that the region 105 illuminated with the lightguide 16K is contiguous with the region 105 illuminated with the lightguide 16L. The transmissive light redirecting member 112 is adjacent thelight emitting surface (e.g., major surface 38 in the embodiment of FIG.18B) of the light guide 90. The transmissive light redirecting member112 is configured to redirect at least some of the light exiting thelight emitting surface in a direction having a vector component directedtowards the light engine 14 to produce light output with a light rayangle distribution 106. Light that is not redirected is represented byarrow 116. Light that is redirected is represented by arrow 114. In oneembodiment, the transmissive light redirecting member 112 is a turningfilm. In another embodiment, the transmissive light redirecting member112 includes optical elements, such as at least one of lenticularoptical elements, prismatic optical elements, or micro-optical elements.

In another embodiment, shown in FIG. 18C, the light guides 16K, 16L areedge lit by the light engine 14. The light guides 16K, 16L emit lightthrough two opposed light-emitting surfaces, namely the major surface 38and the major surface 40 in the illustrated embodiment. Light emittedthrough the major surface 38 facing the illuminated surface 104 isrepresented by arrow 118 and this light is directed away from the lightengine 14 and away from the major surface 38. Light that is emittedthrough the major surface 40 opposite the major surface 38 is incidenton reflective light redirecting member 120 that reflects and redirectsthe light such that the reflected light 122 has a vector componentdirected towards the light engine 14. The reflected light passes backthrough the light guide 102 and exits the major surface 38 travelling ina direction toward the region 105 of surface 104. This light has adirection of travel represented by arrow 122 with a vector componentdirected towards the light engine 14. The reflective light redirectingmember 120 associated with light guide 16K performs the function ofmeans for outputting at least part 122 of the light output from thelight guide 16K with a vector component directed towards the lightengine 14 such that the region 105 illuminated with the light guide 16Kis contiguous with the region 105 illuminated with the light guide 16L.The reflective light redirecting member 120 is adjacent the majorsurface 40 of the light guide 16K and, in one embodiment, is implementedusing a reflective film. In another embodiment, the reflective lightredirecting member 120 is provided by reflective elements on the majorsurface 40 of the light guide 16K. In one embodiment, the reflectivelight redirecting member 120 may be used in conjunction with thetransmissive light redirecting member 112.

Referring to FIGS. 18A-18C, by adjusting the light ray angledistributions 106 of light output by the light guides 16 of the modularlighting assembly 12, the regions 105 may be configured to provide adesired illumination profile on the surface 104. In an example, acontinuous illumination pattern is produced on the surface 104 or theillumination patterns overlap at a defined distance from the surface104. Configuration is accomplished by controlling the angulardistribution of the light input to the light guide(s) 16, selection andarrangement of the light extracting elements 42, and, if present,selection and positioning of the transmissive light redirecting member112 or the reflective light redirecting member 120. The desiredillumination profile may be obtained using two light guides and onelight engine 14 (e.g., the embodiments illustrated in FIGS. 6-10 and18B-18C) or more than two light guides and more than one light engine 14(e.g., the embodiments illustrated in FIGS. 1, 4, 5, 14-17, and 18A).

The modular lighting assemblies can be configured to have angles betweenthe light guides 16 of 180 degrees (e.g., the embodiments illustrated inFIGS. 1, 4, 5, 14, 15 and 18A-18C) or angles between the light guides 16different from 180 degrees (e.g., the embodiments illustrated in FIGS.6-10, 16, 17 and 19). Also, the angles between adjacent light guides inthe modular lighting assembly 12 may be equal or unequal angles. Thelight guides in the modular lighting assembly 12 may be curved orplanar. Moreover, combinations of the foregoing are possible. In theembodiment of FIG. 19, which represents a folded configuration of themodular lighting assembly 12, the light ray angle distributions 106 fromthe light guides 16 are configured so that the illumination at theillumination surface 104 is continuous.

FIG. 20 illustrates another embodiment of the modular lighting assembly12 with hinged light engines 14. The hinged light engines 14 of FIG. 20are similar in construction to the previously described hinged lightengines 14. More specifically, the hinged light engines 14 includecoupling members 76, 78 that are joined at a hinge 123. In theillustrated embodiment, each light guide 16 has a notch 124 that isconfigured to accommodate a portion of respective coupling member 76, 78of the light engine 14 and provides the light input edge 30 of the lightguide 16. Each coupling member 76, 78 has a receptacle 28 thataccommodates part of the light guide 16 adjacent the notch 124. Inputlight from the light source segment 26 of the respective coupling member76, 78 enters the light guide through the light input edge 30. Anelongate slot 24 extends through each coupling member 76, 78 between thelight source segment 26 and the hinge to provide a path for cooling airflow. The modular lighting assembly 12 of the illustrated embodiment issuspended by a respective retaining member 43 affixed to each couplingmember 78.

Referring now to FIG. 21, another embodiment of the modular lightingassembly 12 is shown. In this embodiment, the modular lighting assembly12 is arranged as a track lighting system in which a track 126 retainslighting assemblies 10. The track 126 may be mounted to an architecturalsurface, such as a ceiling or a wall, or may be suspended with retainingmembers 43 (not shown in FIG. 21). The track 126 includes a slot 128that receives a connector that attaches each lighting assembly 10 to thetrack 126. In the illustrated embodiment, the connector is a slotengagement portion 130 of the light engine 14. In one embodiment, thelight engines 14 that are retained by the track 126 are slidable alongthe track 126 to be positioned relative to the track 126 as desired. Inone embodiment, the track 126 retains conductors 132 (illustratedschematically by a broken line) that supply electrical power to thelight engines via power connectors 61 (FIG. 2) that are on the slotengagement portion 130 of the light engine 14.

Opposite the slot engagement portion 130, the light engines 14 retainand supply light to a light guide 16, as described above. In theillustrated embodiments, the light engines 14 that engage the track 126are hinged so that the retained light guides 16 are positionable in arange of angles with respect to the track 126. In other embodiments, thelight engine 14 can additionally or alternatively be configured torotate about an axis normal to the longitudinal axis of the light engine14 (e.g., about an axis normal to the light input edge 30). In thismanner, the light guides 16 of the illustrated embodiments are rotatableabout an axis extending parallel to the major surfaces thereof. Thelight engines 14 can be rotatable and hinged to provide a wide varietyof possible inclinations for the light guides 16. Any of theabove-described light engines 14 may be modified to include thisrotation capability. Also, the slot engagement portion 130 may beattached to the light guide 16.

In the embodiment of FIG. 21, some of the lighting assemblies 10 includea single light engine 14 connected to the track 126 and a single lightguide 16. Although not illustrated, more than one light guide 16 may beretained and edge lit by the light engine 14 that is connected to thetrack 126 with an angular separation between the light guides 16. Otherlighting assemblies 10 in the illustrated embodiment include a firstlight engine 14M that is connected to the track 126, a first light guide16N retained by that light engine 14M, and a second light engine 14Oconnected to the distal edge of the light guide 16N. The second lightengines 14O of the illustrated embodiment are also hinged and retain asecond light guide 16P. Power may be delivered to the second lightengine 14O from the first light engine 14M using conductors 62 (FIG. 1)that are on or in first light guide 16N. Additional light engines 14 andlight guides 16 can be further attached to form various lightingassemblies 10 that are retained by the track 126.

FIGS. 22-24 show an example of another embodiment of the lightingassembly 10. This embodiment is based on the embodiment described abovewith reference to FIGS. 6-10, but uses a hinged light engine 14 with agreater heat dissipation capability. Specifically, each coupling member76, 78 includes a heat sink 130. The light source segment 26 isthermally coupled to the heat sink 130. In the example shown, each heatsink 130 includes fins 134 and internal air passages 136 through whichair may travel (represented by arrows 137) to promote heat dissipationby the heat sink. The greater heat dissipating capacity provided by theheat sink 130 allows the light source segment 26 to include more lightsources 32, supply higher current to the light sources 32 and/or usehigher-power light sources 32.

In some embodiments, the hinge 132 includes a static portion 138 aboutwhich coupling members 76, 78 contra-rotate as the angle α between themis adjusted. The static portion 138 is used to suspend or mount thelighting assembly 10, as shown in FIG. 24, and power connections to thelighting assembly can also be made at the static portion. The couplingmember 76, 78, the heat sink 130, and a portion of the hinge 132 may bea single component or multiple components, and may additionally be madeof a highly thermally conductive material, such as aluminum or copper.

In the example shown, the light guides 16 are planar. In other examples,one or both light guides 16 are curved (e.g., in a manner similar tothat shown in FIGS. 6-10).

FIG. 22 shows two different exemplary configurations of the light guides16. The light guides 16Q, 16R include light extracting elements (notshown) that extract light from the light guides 16Q, 16R through themajor surfaces 38 and 40. The light guide 16R additionally includes areflector 142 adjacent the major surface 40 to reflect light extractedfrom the light guide 16R through the major surface 40 back into thelight guide such that the light passes through the light guide 16R andexits through the major surface 38. The light guide 16Q is configuredfor directly illuminating a surface below the lighting assembly 10 andadditionally for providing a wash of light on another surface above thelighting assembly. In one embodiment this is accomplished by using twoconfigurations of light extracting elements. The first configuration oflight extracting elements extracts light through the major surface 40 ofthe light guide 16Q with a light ray angle distribution in which lowlight ray angles (relative to the major surface 40) predominate. Thesecond configurations of light extracting elements extracts light fromthe major surface 38 of the light guide 16Q with a light ray angledistribution in which medium light ray angles (relative to the majorsurface 38) predominate. Typically, both of the light guides are of thesame type.

In other embodiments, the light engine 14 is not hinged and the couplingmembers 76, 78 are set at a fixed angle relative to one another,suitable for a given application.

FIG. 25 shows an example of another embodiment of the lighting assembly10 having a common light source segment 26 for providing light to bothlight guides 16. The light source segment 26 is coupled to the staticportion 138 of the hinge 136. The light source segment 26 includes aprinted circuit board (PCB) 34 on which back-to-back sets of lightsources 32 are mounted. Coupling members 76, 78 couple the light guides16 to the hinge 136.

Flexible light couplings 150 extend between each light guide 16 and arespective set of the light sources 32. In the example shown, eachflexible light coupling 150 includes a flexible light conductor 152 witha light coupler 154, 156 at each end. Light coupler 154 couples to a setof light sources 32 and light coupler 156 couples to the light inputedge 30 of the respective light guide 16. The flexible light conductor152 flexes as the angle α is adjusted. The light coupler 154 maintainsthe angle of incidence of light on the flexible light conductor 152 asthe flexible light conductor flexes. The light coupler 156 maintains theangle of incidence of light on the light input edge 30 of the lightguide 16 as the flexible light conductor flexes. In an example, theflexible light conductor is an optical fiber or an array of opticalfibers.

In this disclosure, the phrase “one of” followed by a list is intendedto mean the elements of the list in the alternative. For example, “oneof A, B and C” means A or B or C. The phrase “at least one of” followedby a list is intended to mean one or more of the elements of the list inthe alternative. For example, “at least one of A, B and C” means A or Bor C or (A and B) or (A and C) or (B and C) or (A and B and C).

1. A lighting assembly, comprising: a light engine comprising a firstcoupling member and a second coupling member mechanically coupled to thefirst coupling member; a first light guide secured to the first couplingmember; a second light guide secured to the second coupling member; afirst light source retained by the first coupling member and located toedge light a light input edge of the first light guide; and a secondlight source retained by the second coupling member and located to edgelight a light input edge of the second light guide; and wherein thefirst coupling member and the second coupling member are rotatablerelative to each other to adjust an angular position between the firstlight guide and the second light guide, and a light ray angledistribution of light output by the lighting assembly varies as afunction of the angular position between the first light guide and thesecond light guide.
 2. The lighting assembly of claim 1, wherein thefirst coupling member is hingedly attached to the second couplingmember.
 3. The lighting assembly of claim 1, wherein the light enginefurther comprises a static portion to which each of the first and secondcoupling members are mechanically coupled and relative to which each ofthe first and second coupling members rotate.
 4. The lighting assemblyof claim 3, wherein the first and second coupling members contra-rotaterelative to the static portion.
 5. The lighting assembly of claim 1,wherein: each light guide comprises opposed major surfaces between whichthe light input edge extends in a thickness direction and lightextracting elements at at least one of the major surfaces; and lightinput to the light guide through the light input edge propagates in thelight guide by total internal reflection, the light extracting elementsdisrupt said total internal reflection and the disrupted light exits thelight guide via one of the major surfaces.
 6. The lighting assembly ofclaim 5, wherein the light extracting elements are configured to extractlight from the light guide in at least one of a defined intensityprofile or a defined light ray angle distribution.
 7. The lightingassembly of claim 6, wherein the intensity profile is a uniformintensity profile.
 8. The lighting assembly of claim 5, furthercomprising, for at least one of the light guides, a light redirectingelement or a light characteristic changing element juxtaposed with oneof the major surfaces and configured to interact with the light exitingthe light guide.
 9. The lighting assembly of claim 5, wherein theangular position between the first light guide and the second lightguide is any one of: greater than 180 degrees between the respectivemajor surfaces of the light guides through which a majority of lightexits; 180 degrees between the respective major surfaces of the lightguides through which a majority of light exits; and less than 180degrees between the respective major surfaces of the light guidesthrough which a majority of light exits.
 10. The lighting assembly ofclaim 1, further comprising an ambient light sensor and the lightingassembly adjusts light output by the light sources in accordance with adetected level of ambient light to control an overall light level in aspace illuminated by the lighting assembly.
 11. The lighting assembly ofclaim 1, wherein light output by the light sources is controlled as afunction of the angular position between the first light guide and thesecond light guide.
 12. The lighting assembly of claim 1, furthercomprising a means for outputting at least part of the light output fromat least one of the light guides with a vector component directed to thelight source that edge lights the respective light guide.
 13. Thelighting assembly of claim 1, further comprising a retaining membercoupled to the light engine, the lighting assembly suspended by theretaining member.
 14. The lighting assembly of claim 1, wherein eachcoupling member comprises a heat sink.
 15. The lighting assembly ofclaim 1, wherein, relative to a longitudinal axis of the light engine, amajority of light output by the lighting assembly is cast in a downwarddirection.
 16. The lighting assembly of claim 1, further comprising aconnector configured to electrically and mechanically couple the lightengine to a track.
 17. A track-based lighting assembly, comprising: atrack; and a lighting fixture, the lighting fixture comprising: a lightengine comprising a first coupling member and a second coupling membermechanically coupled to the first coupling member, and furthercomprising a connector that electrically and mechanically couples thelight engine to the track; a first light guide secured to the firstcoupling member; a second light guide secured to the second couplingmember; a first light source retained by the first coupling member andlocated to edge light a light input edge of the first light guide; and asecond light source retained by the second coupling member and locatedto edge light a light input edge of the second light guide; and whereinthe first coupling member and the second coupling member are rotatablerelative to each other to adjust an angular position between the firstlight guide and the second light guide, and a light ray angledistribution of light output by the lighting fixture varies as afunction of the angular position between the first light guide and thesecond light guide.
 18. The track-based lighting assembly of claim 17,wherein the track retains plural ones of the lighting fixtures along alength of the track.
 19. The track-based lighting assembly of claim 17,wherein a position of the lighting fixture is adjustable along a lengthof the track.
 20. The track-based lighting assembly of claim 17, whereinthe track is suspended from an architectural surface.
 21. Thetrack-based lighting assembly of claim 17, wherein the track is mountedto an architectural surface.
 22. The track-based lighting assembly ofclaim 17, wherein the light engine is rotatable about an axis normal toa longitudinal axis of the track.
 23. The track-based lighting assemblyof claim 17, wherein the first coupling member and the second couplingmember rotate relative to each other about respective axes that areparallel to a longitudinal axis of the track.
 24. The track-basedlighting assembly of claim 17, wherein the first coupling member ishingedly attached to the second coupling member.
 25. The track-basedlighting assembly of claim 17, wherein the light engine furthercomprises a static portion to which each of the first and secondcoupling members are mechanically coupled and relative to which each ofthe first and second coupling members rotate.
 26. The track-basedlighting assembly of claim 25, wherein the first and second couplingmembers contra-rotate relative to the static portion.
 27. Thetrack-based lighting assembly of claim 17, wherein: each light guidecomprises opposed major surfaces between which the light input edgeextends in a thickness direction and light extracting elements at atleast one of the major surfaces; and light input to the light guidethrough the light input edge propagates in the light guide by totalinternal reflection, the light extracting elements disrupt said totalinternal reflection and the disrupted light exits the light guide viaone of the major surfaces.
 28. The track-based lighting assembly ofclaim 27, wherein the light extracting elements are configured toextract light from the light guide in at least one of a definedintensity profile or a defined light ray angle distribution.
 29. Thetrack-based lighting assembly of claim 28, wherein the intensity profileis a uniform intensity profile.
 30. The track-based lighting assembly ofclaim 27, further comprising, for at least one of the light guides, alight redirecting element or a light characteristic changing elementjuxtaposed with one of the major surfaces and configured to interactwith the light exiting the light guide.
 31. The track-based lightingassembly of claim 27, wherein the angular position between the firstlight guide and the second light guide is any one of: greater than 180degrees between the respective major surfaces of the light guidesthrough which a majority of light exits; 180 degrees between therespective major surfaces of the light guides through which a majorityof light exits; and less than 180 degrees between the respective majorsurfaces of the light guides through which a majority of light exits.32. The track-based lighting assembly of claim 17, further comprising anambient light sensor and the lighting assembly adjusts light output bythe light sources in accordance with a detected level of ambient lightto control an overall light level in a space illuminated by the lightingassembly.
 33. The track-based lighting assembly of claim 17, whereinlight output by the light sources is controlled as a function of theangular position between the first light guide and the second lightguide.
 34. The track-based lighting assembly of claim 17, furthercomprising a means for outputting at least part of the light output fromat least one of the light guides with a vector component directed to thelight source that edge lights the respective light guide.
 35. Thetrack-based lighting assembly of claim 17, wherein each coupling membercomprises a heat sink.
 36. The track-based lighting assembly of claim17, wherein, relative to a longitudinal axis of the track, a majority oflight output by the lighting fixture is cast in a downward direction.